Nitration of aromatic hydrocarbons



Patented Nov. 1, 1 93 8.

ES PAT EN 7 2,135,012 NlTRATION OF AROMATIC HYDROCARBONS Josef Meissner, Burbach kreis Siegen, Germany Application October 31, 1935, Serial No. 47,727 In Germany November 28, 1934 4 Claims. (01. 260-645) This invention relates to improvements in the vanes 5 for emulsifying the mixtureat its upper nitration of aromatic hydrocarbons. The object part. At the bottom of the vessel a valve 2 is of the invention is to provide a process which alprovided for introducing the nitrating acid, lows continuous nitration of hydrocarbons and whereas a pipe I is provided at the upper part of 5 which has the advantage that a. safe operation the vessel [or introducing the hydrocarbons to be 5 and a good output are obtained while using an nitrated. The mixture is discharged through apparatus of very small dimensions. the port 1. Inlet 8 and outlet 9 respectively serve Heretofore nitroproducts of the kind referred to for introducing the cooling medium into the have been produced in a relatively large appacooling system 6 and for discharging the cooling 1o ratus and by methods employing a number of medium from such cooling system.

, separate operations. These methods were dis- After the apparatus has been filled with niadvantageous in that it was very difficult to distrating acid the material to be nitrated, as for sipate the heat of reaction and to reduce the example toluene, *is introduced through the pipe time of reaction to a minimum. Other disad- I. At the same time the agitating device is vantages such as incomplete mixing of the nistarted in order to obtain a complete mixture of 15 trating mixture and insufficient accessibility of the components, which is very essential for cmthe nitrating acid to the armotic hydrocarbons cicnt nitration. By the action of the agitating to be nitrated are of special note. These disaddevice, the mixture is not only Stirred but also vantages are of great influence on nitration procemulsified as air is introduced into the nitrating esses and reduce their output considerably. mixture in a finely divided state. This causes a 20 With the new process it is possible to'nitrate subdivision of the nitrating mixture into small the aromatic hydrocarbons thoroughly in one drops, whereby a greater nitrating surface is working step, and to avoid the drawbacks reproduced. This, in turn, causes an acceleration ferred to above completely. of the nitrating process and a more uniform The new process consists in continually introproduct. It was found that by emulsifying the 25 ducing the hydrocarbons to be nitrated into the mixture with air the formation of nitric oxides upper part of a vessel which is provided with a could be disposed of almost entirelypipe cooling system and in continually introduc- The air which is distributed in the mixture in ing the nitrating acid into the lower part of said a very finely divided state makes possible a very vessel whereby a forced circulation is obtained quick separation of the nitrated material from 0 within the vessel, the nitrated material being disthe adhering waste acid in the separator (not charged at the upper part of the nitrating vessel. shown). By introducng the nitrating acid into By this arrangement a preliminary nitration is the lower part of the nitrating vessel at 2 the obtained in the upper part of the vessel as, at this nitrating d, which is diluted y the p i na y point, the nitrating acid which has been intronitration, is replaced by the fresh acid and a 35 duced at the lower part of the nitrating vessel final nitration is obtained at this point. This has been partly consumed and therefore diluted, fina ni ra o Co previously o y be O a e whereas the final nitration tal res place in the by a process employing Several Separated p lower part of the vessel where the fresh nitrating The fact that the nitrating mixture is forced 4o acid is introduced. In order to obtain a comthrough the space between the cooling system 6 o plete mixture of the nitrating components and to during t e ion process is of special improduce an emulsion of the nitrating mixture by portanca In h w y the heat f e t n is the introduction of finelydivided air, the mixture dissipated more rapidly than has heretofore been within the nitrating vessel is stirred by an agipos ib e n the own nitrating d v e tating device which has a mixing propeller at its The nitrating mixture discharged at the upper 45 lower part and vanes for emulsifying purposes part of the vessel through the opening I is proat its upper part. portional to the amount of aromatic hydrocar- A preferred embodiment of an apparatus for bons introduced into the upp p f the icarrying out the new nitrating process is illustrating vessel and the amount of nitrating acid trated in the accompanying drawing by a secintroduced into the lower part of said vessel. 5 tional view. The advantages obtained with the new process Referring to the drawing, a nitrating vessel is may be shortly summarized as follows: shown provided with a pipe cooling system 6 and. 1. Continuous nitration by circulating the nian agitating device 3. This agitating device cartrating mixture. ries a mixing propeller e at its lower part and 2. Great nitrating surface by intensively stir- 5 circulation.

acid to come into by emulsifying the nitrating mixture withrair. I

separation of-the nitrated mix- 4. Accelerated ture. in the separator caused by the presence of the air which has been distributed in a finely divided state in the mixture.

5. Intensive cooling of the finely divided nitrating mixture in the nitrating vessel because on the pipe cooling system. I

6. Large output of a nitrating apparatus which has small dimensions, this feature being of special advantage when working with explosives."

What I claim is: L

1. In a process for the continuous nitrationrof aromatic hydrocarbons the steps comprising introducing the material to be nitrated into the upper part of a vessel, introducing into said vessel a cooling fluidin heat exchange relation with the reactant materialbut not in direct contact therewith, introducing the nitrating acid into the lower part of said vessel, providing a forced circulationof, the ensuing mixture in a downward and upward direction said circulation causing partly consumed nitrating acid to come into contact with the fresh material to be nitrated which is introduced into the upper part of the vessel to effect a preliminary nitration thereof, and said causing such preliminarily nitrated material to nitrating acid which is introduced into the lower part of the vessel to effect final nitration thereof.

2. In a process for the continuous nitration of aromatic hydrocarbons the steps comprising introducing the material to be nitrated into the upper part of a vessel, introducing into said vessel a cooling fluid in heat exchange relation with the reactant material but not in direct contact therewith, introducingthe nitrating acid into the lower part of said vessel, emulsifying the ensuing mixture, providing a forced circulation of said mixture in a downward and upward direction said circulation causing partly consumed nitrating contact with the fresh material anemia nitrated mixture at the troducing the material upper part come into contact'with the fresh to be nitrated which is introduced into the upper part of the vessel to effect a preliminary nitration'thereof, and said preliminarily nitrated material, to come into contact with the fresh nitrating acid which is introduced into the lower part of the vessel to eii'ect final nitration thereof, and discharging the upper part of the vessel.

3. In a process for the continuous nitration of aromatic'hydrocarbons the steps comprising 'into be nitrated into the of a vessel, introducing into said ves sel a cooling fluid in heat exchange relation with the reactant material but not in direct contact therewith, introducing the nitrating acid into circulation causing such the lower part of said vessel, heating air into the ensuing reactant mixture to emulsify the same,

providing a-forced circulation of such mixture in a. downward and upward direction, said circulation causing partly consumed nitrating acid to come into contact with the fresh material to be nitrated which is introduced into the upper part of the vessel to effect a preliminary nitration thereof, and said circulation causing such preliminarily nitrated material to come into contact with the fresh nitrating acid which is introduced into the lower. part of the vessel to effect final nitration thereof, and discharging the nitrated mixture at the upper part of the vessel;

-4'. In a process for the continuous nitration of aromatic hydrocarbons the steps comprising introducing the material to be nitrated into the upper part of a vessel, introducing nitrating acid into the lower part of the vessel, beating air into the mixture, circulating the portion of the mixture containing the fresh nitrating acid upwardly and in heat exchange relationship with a coolingfiuid but not in direct contact therewith, contacting the ensuing partly consumed nitrating acid with the fresh material to be nitrated, and

circulating such mixture downwardly to eifect I JOSEF' MEISSNER. 

